1. Field of the Invention
The present invention relates to means for providing hydraulic power to an agricultural implement, in particular to a hydraulic power system for an implement including a flow-rate indicator.
2. Description of Background Art
It is well known in the art to provide towed or carried agricultural implements with a hydraulic pump, e.g. a gear pump, for supplying power to one or more hydraulic actuators. Such gear pump can be driven by the Power-Take-Off (PTO) shaft of the agricultural tractor which tows or carries the implement. For each apparatus it is possible to find an appropriate pump which provides the required flow rate and/or pressure. However, the hydraulic pump on each implement adds to the cost thereof.
Meanwhile it is also conventional to equip medium- or top-range tractors with a hydraulic pump for providing auxiliary power to an implement. One or more pairs of standard connectors allow for a direct connection of the implement circuitry to the hydraulic system on the tractor. The operator can control the hydraulic components on the implement through handles and/or knobs inside the tractor cab. The use of such tractor-mounted pumps solves the problem of providing a distinct pump on each implement. The pump on the vehicle may be selected to provide a maximum flow rate suitable for the largest implements. However, such design will result in poor overall efficiency because most implements require a considerably smaller amount of oil and most oil would flow back to the tank via a pressure-relief valve.
It is possible to use a variable-flow-rate pump and to adapt the pump output to the needs of the implement. However, the required minimum flow rate may vary substantially per implement and, frequently, the operator only notices that the flow rate is too low when the implement is not working adequately. When he adapts the flow rate, he may very well exceed the needed minimum value, such that hydraulic power may be lost unnecessarily.